Following a daytime count, former councillor Christine Iredale won at Golcar on a big recovery from last year’s main polls when she was defeated in the ward.
Labour took a seat from Liberal Democrats at Eastfield, Scarborough Borough, after their candidate withdrew from the contest. Winner Tony Randerson is also a North Yorkshire county councillor.
Golcar is in the Colne Valley parliamentary constituency where, at the general election, Tories won from Labour, who were pushed into third place by Liberal Democrats.
If voting movements between the 2010 council poll in the ward - fought on the same day as the general election - and this week’s by-election were repeated in 2015, Lib Dems would return an MP.
Colne Valley is traditionally a major battleground, with all three parties winning there during the past half-century.
Ukip came second at Scarborough.
Conservative Gary Key received an early Christmas present when he found he had no opponents after nominations closed at Topcliffe, Hambleton District, North Yorkshire.
He was returned unopposed in the by-election, originally scheduled for December 12.
Analysis of four comparable results this week suggests a 5.9% projected nationwide Labour lead over Tory.
Hambleton District - Topcliffe: C unopposed. (May 2011 - C 550, Lib Dem 185). C hold.
Kirklees Borough - Golcar: Lib Dem 1591, Lab 901, Ukip 450, Green 210, C 189. (May 2012 - Lab 1729, Lib Dem 1584, C 548, Green 490). Lib Dem gain from Lab. Swing 11.9% Lab to Lib Dem.
Scarborough District - Eastfield: Lab 310, Ukip 175, Ind 97, C 32, Green 11, Ind 10. (May 2011 - Three seats Lib Dem 468, 358, 356, Lab 272, 260, 240, No description 107, Ind 97, C 91, 81). Lab gain from Lib Dem. Swing 12.8% C to Lab.